Self-powered ultraviolet photodetector based on a single ZnO tetrapod PEDOT:PSS heterostructure

A new ultraviolet (UV) photodetector based on a single ZnO tetrapod and PEDOT:PSS heterostructure was constructed and investigated. At zero bias, the detector showed an on off ratio of ∼1100, a rise time of ∼3.5 s and a decay time of ∼4.5 s when the 325 nm UV (0.16 mW) illuminated the p-n heterojunction. The self-powered properties were driven by the photovoltaic effect, with a short-circuit current of ∼1.1 nA, an open-circuit voltage of ∼0.2 V and a fill factor of ∼25%. Furthermore, self-powered properties were also found when the UV irradiated the ZnO tetrapod only, and the short-circuit current and the open-circuit voltage decreased with the increasing distance between the illuminated spot at the ZnO tetrapod and the heterojunction. The mechanisms for the performances of the detector were examined and discussed. In consideration of the multiterminal feature of ZnO tetrapods, our work provides a possible new approach to developing independent and multifunctional nanodevices.